I really dig 'Let It Rock', and this is reputed to be the only version ever played by the Grateful Dead. If you want to get your socks knocked off, dig around for recordings of Jerry and Merle Saunders' band, Legion of Mary. Listen to them do this song with brass. I would suggest 1974-11-15 Worcester Polytech. The Marx Medows recording is also stellar, but doesn't cover this song. Great sound! I got it from
Furthur.net. The Legion of Mary stuff is incredibly fantastic, jazzy and rocking at the same time, I would say it is some of Jerry's most inspired guitar work and really truly wonderful arrangements of interesting songs.
I'm not reviewing this recording, so much as sending out a 'heads up' for those deadheads who might not have discovered Legion of Mary yet, especially Jerry fans, find some and listen, for me it was like discovering a direction the Dead might have gone in an alternate universe that I only wish I lived in.